Skip to main content
. 2016 Mar 10;3(1):ENEURO.0138-15.2016. doi: 10.1523/ENEURO.0138-15.2016

Figure 1.

Figure 1.

Pleasantness and intensity of brushing in healthy participants and chronic pain patients. Healthy participants and FM patients rated the pleasantness (A, B) and intensity (C, D) of slow (CT-optimal) and fast brushing of the left forearm on the corresponding VAS scales. Mean ratings at baseline (before any drug administration) are displayed; error bars show SD. *Two-tailed Tukey test, p < 0.05. Lines display individual participant data. There was a significant main effect of brushing speed (slow vs fast) on pleasantness ratings (F(1,50) = 3.56, one-tailed p = 0.032 a; without males: F(1,46) = 3.76, one-tailed p = 0.027) but no main effect of group (healthy vs FM; F(1,50) = 0.41, one-tailed, p = 0.26 b; without males: F(1,46) = 0.32, one-tailed, p = 0.26). There was a significant interaction between brushing speed and group (F(1,50) = 3.32, one-tailed, p = 0.037c; Cohen’s d = 0.51; without males: F(1,46) = 3.14, one-tailed, p = 0.04; A shows mean slow–fast ratings). Post hoc Tukey tests showed that healthy participants rated slow brushing as significantly more pleasant than fast brushing (Tukey, p = 0.042), whereas FM participants did not (Tukey, p = 1.00; A shows mean slow–fast ratings). Age did not affect ratings of brushing pleasantness or interact with speed in healthy participants (F(1,26) = 0.03, p = 0.86d; F(1,26) = 0.09, p = 0.76e) or in FM patients (F(1,22) = 0.56, p = 0.46f; F(1,22) = 3.08, p = 0.09g). When depression and anxiety were added to the model, depression significantly predicted pleasantness ratings (F(1,46) =4.28, p = 0.04); anxiety did not (F(1,46) = 0.42, p = 0.52). Including these ratings in the model strengthened the group by speed interaction (F(1, 48) = 4.42, two-tailed, p = 0.041). There was a significant main effect of speed of brushing (slow vs fast) on intensity ratings (F(1,50) = 4.26, p < 0.001h; without males: F(1,46) = 20.0, p < 0.001) but no main effect of group (healthy vs FM; F(1,50) = 0.32, one-tailed, p = 0.58 i; without males: F(1,46) = 0.19, two-tailed p = 0.67). There was a significant interaction between brushing speed and participant group (F(1,50) = 4.26, p = 0.044 j; Cohen’s d = 0.57; without males: F(1,46) = 4.42, p = 0.041,). Post hoc Tukey tests showed that healthy participants rated fast brushing as more intense than slow brushing (Tukey p < 0.001), whereas FM participants did not (Tukey p = 0.24; B shows mean slow–fast ratings). Age did not affect ratings of brushing intensity or interact with speed in either healthy participants (F(1,26) = 1.09, p = 0.31k; F(1,26) = 0.11, p = 0.75l) or FM patients (F(1,22) = 0.01, p = 0.93m; F(1,22) = 0.05, p = 0.83n). Anxiety significantly predicted pleasantness ratings (F(1,46) = 6.66, p = 0.01); depression did not (F(1,46) = 1.34, p = 0.25). Including these ratings in the model weakened the group by speed interaction (F(1,48) = 3.67, two-tailed p = 0.061).